Method and apparatus for selective nitridation process

ABSTRACT

Embodiments of the disclosure provide an improved apparatus and methods for nitridation of stacks of materials. In one embodiment, a method for processing a substrate in a processing region of a process chamber is provided. The method includes generating and flowing plasma species from a remote plasma source to a delivery member having a longitudinal passageway, flowing plasma species from the longitudinal passageway to an inlet port formed in a sidewall of the process chamber, wherein the plasma species are flowed at an angle into the inlet port to promote collision of ions or reaction of ions with electrons or charged particles in the plasma species such that ions are substantially eliminated from the plasma species before entering the processing region of the process chamber, and selectively incorporating atomic radicals from the plasma species in silicon or polysilicon regions of the substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 13/536,443, filed Jun. 28, 2012, which claims benefit of U.S.provisional patent application Ser. No. 61/522,129, filed Aug. 10, 2011,which is herein incorporated by reference.

BACKGROUND Field of the Disclosure

Embodiments of the present disclosure generally relate to manufacturingsemiconductor devices. More specifically, embodiments described hereinrelate to manufacture of floating gate NAND memory devices and othertransistor gate structures using an improved plasma applicator.

Description of the Related Art

Flash memory, such as NAND flash memory devices, is a commonly used typeof non-volatile memory in widespread use for mass storage applications.The NAND flash memory devices typically have a stacked type gatestructure in which a tunnel oxide (TO), a floating gate (FG), aninter-poly dielectric (IPD), and a control gate (CG) are sequentiallystacked on a semiconductor substrate. The floating gate, the tunneloxide, and the underlying portion of the substrate generally form a cell(or memory unit) of the NAND flash memory device. A shallow trenchisolation (STI) region is disposed in the substrate between each celladjacent to the tunnel oxide and the floating gate to separate the cellfrom adjacent cells. During writing of the NAND flash memory devices, apositive voltage is applied to the control gate which draws electronsfrom the substrate into the floating gate. For erasing data of the NANDflash memory devices, a positive voltage is applied to the substrate todischarge electrons from the floating gate and through the tunnel oxide.The flow of electrons is sensed by a sensing circuitry and results inthe returns of “0” or “1” as current indicators. The amount of electronsin the floating gate and “0” or “1” characteristics form the basis forstoring data in the NAND flash memory devices.

The floating gate is typically isolated from the semiconductor substrateby the tunnel oxide and from the control gate by the inter-polydielectric, which prevents the leakage of electrons between, forexample, the substrate and the floating gate or the floating gate andthe control gate. To enable continued physical scaling of the NAND flashmemory device, a nitridation process has been used by the industry toincorporate nitrogen into the surface of the floating gate to improvethe reliability of the tunnel oxide or to suppress dopant diffusion outof the floating gate. However, the nitridation process also undesirablyincorporates nitrogen into shallow trench isolation regions. Nitrogenincorporated in the shallow trench isolation region between neighboringfloating gate structures forms a charge leakage path which cannegatively impact final device performance.

Therefore, there is a need for improved methods and an apparatus fornitridation of stacks of materials.

SUMMARY OF THE DISCLOSURE

The present disclosure generally provides a method and an apparatus forincorporating radicals of a plasma into a substrate or a material on asemiconductor substrate using a remote plasma source. In one embodiment,a remote plasma system includes a remote plasma chamber defining a firstregion for generating a plasma comprising ions and radicals, a processchamber defining a second region for processing a semiconductor device,the process chamber comprising an inlet port formed in a sidewall of theprocess chamber, the inlet port being in fluid communication with thesecond region, and a delivery member for delivering plasma species fromthe remote plasma chamber to the process chamber, the delivery memberincluding a body defining a longitudinally extending passageway therein,the body having a first end connecting to the first region and a secondend connecting to the second region, the second end being opposed to thefirst end, wherein the passageway is coupled to the inlet port of theprocess chamber such that a longitudinal axis of the passagewayintersects at an angle of about 20 degrees to about 80 degrees withrespect to a longitudinal axis of the inlet port. In one example, thedelivery member further includes a flange extending around an outersurface of the body at the second end, the flange having a surfacesubstantially flush with a surface of a sidewall of the process chamber.

In another embodiment, a remote plasma system, including a remote plasmachamber defining a first region for generating a plasma comprising ionsand radicals, a process chamber defining a second region for processinga semiconductor device, the process chamber comprising an inlet portformed in a sidewall of the process chamber, the inlet port being influid communication with the second region, and a delivery memberdisposed between the remote plasma chamber and the process chamber andhaving a passageway in fluid communication with the first region and theinlet port, the delivery member being configured such that alongitudinal axis of the passageway intersects at an angle of about 20degrees to about 80 degrees with respect to a longitudinal axis of theinlet port.

In yet another embodiment, a method for processing a semiconductordevice in a processing region of a process chamber is disclosed. Themethod includes generating and flowing plasma species from a remoteplasma source to a delivery member having a longitudinal passageway,flowing plasma species from the passageway to an inlet port formed in asidewall of the process chamber, wherein the plasma species are flowedat an angle into the inlet port to promote collision of ions or reactionof ions with electrons or charged particles in the plasma species suchthat ions are substantially eliminated from the plasma species beforeentering the processing region of the process chamber, and selectivelyincorporating atomic radicals from the plasma species in silicon orpolysilicon regions of the semiconductor device.

In one another embodiment, a method for processing a substrate in aprocessing region of a process chamber is provided. The method includesgenerating and flowing plasma species from a remote plasma source to adelivery member having a longitudinal passageway, flowing plasma speciesfrom the longitudinal passageway to an inlet port formed in a sidewallof the process chamber, wherein the plasma species are flowed at anangle into the inlet port to promote collision of ions or reaction ofions with electrons or charged particles in the plasma species such thations are substantially eliminated from the plasma species beforeentering the processing region of the process chamber, and selectivelyincorporating atomic radicals from the plasma species in silicon orpolysilicon regions of the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIG. 1 illustrates a schematic cross-sectional view of an exemplarysemiconductor device that can be made with a method and an apparatusaccording to one embodiment of the disclosure.

FIG. 2 illustrates a schematic view of a remote plasma system inaccordance with one embodiment of the disclosure.

FIG. 3 illustrates a schematic and fragmentary cross-sectional side viewof an exemplary delivery pipe for use in supplying radicals of a plasmato an RTP apparatus according to one embodiment of the disclosure.

FIG. 4 illustrates a schematic and fragmentary top view of a deliverypipe of FIG. 3 and an RTP apparatus in accordance with an embodiment ofthe disclosure.

DETAILED DESCRIPTION

The disclosure describes an apparatus and method for incorporatingradicals of a plasma into a substrate or a material on a semiconductorsubstrate using a remote plasma source. In general, plasma sourcesgenerated by, for example, an energetic excitation of gaseous moleculesconsist of a plasma of charged ions, radicals, and electrons. Thedisclosure recognizes that radicals of a plasma react in a much moredesirable manner with silicon or polysilicon material on a substrate,than ions or a mixture of radicals and ions. In that regard, thedisclosure provides an apparatus and a method of eliminating themajority of the ions of the plasma such that only radicals of the plasmareact with silicon or polysilicon material on a substrate, therebyobtaining a greater selectivity of processing of silicon or polysiliconmaterial on the substrate.

While the present disclosure is not to be limited to a particulardevice, the apparatus and methods described can be used for themanufacture of semiconductor devices and structures suitable for narrowpitch applications. As used herein, narrow pitch applications includehalf-pitches of 32 nm or less (e.g., device nodes of 32 nm or less). Theterm “pitch” as used herein refers to a measure between the parallelstructures or the adjacent structures of the semiconductor device. Thepitch may be measured from side to side of the same side of the adjacentor substantially parallel structures. The semiconductor devices andstructures may be utilized in applications having greater pitches aswell. The semiconductor devices may be, for example, NAND or NOR flashmemory, or other suitable devices.

Exemplary NAND Flash Memory Device

FIG. 1 illustrates a schematic cross-sectional view of an exemplarysemiconductor device, such as a NAND flash memory device 100, that canbe made with the apparatus of the present disclosure. The memory device100 generally includes a substrate 102 having a tunnel oxide layer 104disposed thereon. A floating gate 106 is disposed on the tunnel oxidelayer 104. The floating gate 106, the tunnel oxide layer 104, and theunderlying portion of the substrate 102 form a cell 103 (or memory unit)of the memory device 100. Each cell 103 of the memory device 100 may beseparated, for example, by a shallow trench isolation (STI) region 108which is disposed in the substrate 102 between each cell 103 (e.g.,adjacent to the tunnel oxide layer 104 and floating gate 106, where theSTI region 108 separates the cell 103 from adjacent cells 105 and 107).The memory device 100 further includes a control gate layer 112 and aninter-poly dielectric (IPD) layer 110 disposed between the floating gate106 and the control gate layer 112. The IPD layer 110 separates thefloating gate 106 from the control gate layer 112.

The substrate 102 may include a suitable material such as crystallinesilicon (e.g., Si<100> or Si<111>), silicon oxide, strained silicon,silicon germanium, doped or undoped polysilicon, doped or undopedsilicon wafers, patterned or non-patterned wafers, silicon on insulator(SOI), carbon doped silicon oxides, silicon nitride, doped silicon,germanium, gallium arsenide, glass, sapphire, or the like. In someembodiments, the substrate 102 comprises silicon.

The tunnel oxide layer 104 may include silicon and oxygen, such assilicon oxide (SiO₂), silicon oxynitride (SiON), or high-k dielectricmaterials, such as aluminum—(Al), hafnium—(Hf), or lanthanum—(La),zirconium—(Zr) based oxides or oxynitrides, or silicon nitrides(Si_(x)N_(y)), in single or layered structures (e.g., SiO₂/high-k/SiO₂),or the like. The tunnel oxide layer 104 may have any suitable thickness,for example, between about 5 nm to about 12 nm. The tunnel oxide layer104 may have a width, within each cell, substantially equivalent to thewidth of a base of the floating gate 106. The STI region 108 may includesilicon and oxygen, such as silicon oxide (SiO₂), silicon oxynitride(SiON), or the like.

The floating gate 106 typically includes a conductive material, such assilicon, polysilicon, metals, or the like. The floating gate 106 has aconfiguration suitable to facilitate disposing portions of the controlgate layer 112 between adjacent cells (e.g., between cells 103, 105, and107). As such, the floating gate may be formed in an inverted “T” shape.As used herein, the term inverted “T” refers generally to the geometryof the structure wherein an upper portion of the floating gate 106 isrelieved with respect to a base of the floating gate 106. Such reliefprovides room for the IPD layer 110 to be formed over the floating gate106 without completely filling the gap between adjacent floating gates106, thereby allowing a portion of the control gate layer 112 to bedisposed between adjacent floating gates 106.

The IPD layer 110 may include any suitable single or multi-layerdielectric materials. An exemplary single layer IPD may include SiO₂,SiON, or a high-k dielectric material as discussed above with respect totunnel oxide layer 104, or the like. An exemplary multi-layer IPD may bea multi-layer “ONO” structure (not shown) including a first oxide layer,a nitride layer, and a second oxide layer. The first and second oxidelayers typically include silicon and oxygen, such as silicon oxide(SiO₂), silicon oxynitride (SiON), or the like. The nitride layertypically comprises silicon and nitrogen, such as silicon nitride (SiN),or the like. In some embodiments, a multi-layer IPD layer comprisingSiO₂/high-k/SiO₂ (such as, SiO₂/Al₂O₃/SiO₂) can also be used as the IPDlayer 110. The IPD layer 110 may be deposited to a thickness of betweenabout 10 nm to about 15 nm.

The control gate layer 112 may be deposited atop the IPD layer 110 toform a control gate. The control gate layer 112 typically comprises aconductive material, such as polysilicon, metal, or the like. Theinverted T shape of the floating gate 106 enables a larger surface area,located between adjacent floating gates (for example, those of cells 103and 105), for the control gate late 112. The increased surface area ofthe control gate layer 112 may advantageously improve capacitivecoupling between a sidewall of the floating gate 106 and the controlgate, and may reduce parasitic capacitance between adjacent floatinggates, floating gate interference, noise, or the like.

Optionally, prior to IPD deposition, a dielectric layer 113 may beconformally formed on the exposed surface of the floating gate 106.Specifically, the dielectric layer 113 is selectively formed mainly onthe exposed surface of the floating gate 106, with little or noformation of the dielectric layer 113 on the STI region 108 or any otherdielectric films under the identical plasma conditions (will bediscussed in detail below). With the dielectric layer 113 selectivelyformed mainly on floating gate 106, the reliability of the tunnel oxideand/or suppression of dopant diffusion out of the floating gate 106 areimproved while enabling scaling of the IPD film stack thickness.

The dielectric layer 113 may be a nitride layer such as silicon nitrideor silicon oxynitride. The nitride layer may be formed by exposing thefield surface 114 and sidewall 115 of the floating gate 106 to nitrogencontaining radicals. Nitrogen containing radicals, such as N, NH, andNH₂, may be created with the aid of some excitation, for instance, aplasma excitation, a photo excitation, an electron-beam excitation, orintense heat. Nitridation process may be performed by thermal meansalone, by plasma means alone, or by a combination of the two. In oneembodiment, the surfaces of the floating gate 106 are exposed tonitrogen containing radicals using a selective plasma nitridationprocess. The nitrogen containing radicals will react preferentially withthe surface of the floating gate 106 (formed of silicon or polysilicon,for example) during the selective plasma nitridation process, ratherthan the surface of the STI region 108 (formed of silicon oxide, forexample) due to lower Si-Si bond-breaking energies (222 kJ/mol) comparedto Si—O bond-breaking energies (452 kJ/mol). As radicals are notreactive enough to break Si—O bond, the selective plasma nitridationprocess forms nitrides of silicon faster than nitrides of silicon oxide,resulting in a significantly greater concentration ofnitrogen-containing material, i.e., dielectric layer 113 formed of, forexample, Si-N bonds, at the field surface 114 and sidewall 115 of thefloating gate 106 as opposed to STI region 108 between the adjacentfloating gates 106. Since the nitrogen-containing material or dielectriclayer 113 is not present in significant amounts at STI region 108, theundesired charge leakage path between neighboring floating gatestructures does not occur.

Radicals are preferred because ions have high chemical activity comparedto radicals and compared to the bond energies listed above (1^(st)ionization energy of N₂=1402 kJ/mol; atomization energy of N₂=473kJ/mol), so ions do not achieve the selectivity of radicals.Selectivity, defined as concentration of nitrogen in silicon divided byconcentration of nitrogen in oxide after a given deposition process, maybe between about 10:1 and about 100:1, such as between about 20:1 andabout 70:1, for example about 40:1. Greater exposure time may improvethe selectivity.

High radical density versus ion density may be achieved by a highpressure plasma process using, for example, a pressure between about 0.3Torr and 20 Torr, for example, about 5 Torr or above. The high pressureencourages ions to recombine with electrons quickly, leaving neutralradical species and inactive species. In some embodiments, a radical gasis formed. In some embodiments, remote plasma may be used to selectivelygenerate radical species by various methods. The remote plasmagenerator, for example a microwave, RF, or thermal chamber, may beconnected to a processing chamber through a delivery pipe. The deliverypipe, as will be described in more detail below with respect to FIGS. 3and 4, may be a relatively long pathway positioned at an angle relativeto the processing chamber to encourage recombination of ionic speciesalong the pathway before reaching the processing region. The radicalsflowing through the delivery pipe may flow into the chamber through ashowerhead or radical distributor, or through a portal entry in a sidewall of the chamber at a flow rate between about 1 sLm and about 20 sLm,such as between about 5 sLm and about 20 sLm, for example about 10 sLm.Higher pressures and lower flows are believed to promote collisions.Nitrogen radicals may be formed in one embodiment by exposing a nitrogencontaining gas, such as nitrogen, ammonia, or a mixture thereof,optionally with a carrier gas such as helium, to microwave power betweenabout 1-3 kW at a pressure above about 5 Torr. The nitridation processmay be performed at a substrate temperature between about 300° C. andabout 1200° C., for example between about 800° C. and about 1000° C.,which may be increased as the nitridation proceeds to combat surfacesaturation. Heating may be performed using lamp heating, laser heating,use of a heated substrate support, or by plasma heating.

In certain embodiments, various ion filters, such as electrostaticfilters operated at a bias of, for example, about 200V (RF or DC), wireor mesh filters, or magnetic filters, any of which may have a dielectriccoating, may be used between the remote plasma source and the processingchamber. In other embodiments, residence time in the remote plasmagenerator may be modulated using gas flow of reactive species such asnitrogen containing species or gas flow of non-reactive species such asargon or helium. In some embodiments, radical half-life may be extendedby using an ion filter with low pressure plasma generation. Low pressureoperation may be facilitated by integrating a processing chamber with aremote plasma chamber without using an 0-ring to seal the pathwaybetween the two chambers. Uniformity of radical flow into a processingchamber from remote plasma generation chamber may be improved using ashaped connector to provide intimate control of flow patterns.

In some embodiments, an in situ plasma generation process may be used,energized for example by microwave, UV, RF, or electron synchrotronradiation, with an ion filter, such as any of the ion filters describedabove, or an ion shield, such as a mesh or perforated plate, disposedbetween the gas distributor and the substrate support in the chamber. Inone embodiment, a showerhead with ion filter capability (e.g.,electrically isolated or with controlled electric potential) may bedisposed between a plasma generation zone and the substrate processingzone to allow radicals to enter the substrate processing zone whilefiltering ions.

The disclosure as described herein contemplates that substantially allions present in the plasma at the plasma generation (with the radicals)are eliminated prior to coming in contact with the surface of thefloating gate 106 (formed of silicon or polysilicon, for example) duringthe selective plasma nitridation process, rather than the surface of theSTI region 108 (formed of silicon oxide, for example). One waypositively charged ions are eliminated is by combining with electrons(also present in the plasma at the plasma generation) to return to anon-ionic or charge neutral state. A plasma may be substantially free ofthe majority of the ions by separating the plasma generation source fromthe substrate location, e.g., the reaction site, by a distance longerthan the lifetime of the ions at a given plasma discharge rate. In thismanner, the radicals survive the travel distance to the substrate, butions do not and instead lose their ionic character and become chargeneutral.

Exemplary Remote Plasma System

FIG. 2 illustrates an exemplary remote plasma system 200 may benefitfrom embodiments of the present disclosure. Particularly, the remoteplasma system 200 may be used to selectively form a nitride layer on asilicon or polysilicon surface of a semiconductor structure, such as aNAND flash memory device 100. The remote plasma system 200 may include arapid thermal processing (RTP) apparatus 201, such as Centura® RTPcommercially available from Applied Materials, Inc., located in SantaClara, Calif. Other types of thermal reactors may be substituted for theRTP apparatus such as, for example, RPN, RPO, Vantage RadiancePlus™ RTP,Vantage RadOX™ RTP, Radiance® RTP, or other similar chambers/reactorsavailable from Applied Materials Inc. of Santa Clara, Calif.

As can be seen in FIG. 2, coupled to the RTP apparatus 201 is a plasmaapplicator 280 used to remotely provide radicals of a plasma to the RTPapparatus 201. The RTP apparatus 201 generally includes a processingregion 213 enclosed by a side wall 214 and a bottom wall 215. The upperportion of side wall 214 may be sealed to a window assembly 217 by “0”rings. A radiant energy light pipe assembly 218 (enclosed by an upperside wall 224) is positioned over and coupled to window assembly 217.Light pipe assembly 218 may include a plurality of tungsten halogenlamps 219 each mounted into light pipes 221 and positioned to adequatelycover the entire surface area of wafer or substrate 101. Window assembly217 may include a plurality of short light pipes 241. A vacuum can beproduced in the plurality of light pipes 241 by pumping through a tube253 connected to one of the light pipes 241 which is in turn connectedto the rest of the pipes.

Wafer or substrate 101 containing the NAND flash memory device 100 issupported by a support ring 262 within a processing region 213. Supportring 262 is mounted on a rotatable cylinder 263. By rotating cylinder263, support ring 262 and wafer or substrate 101 are caused to rotateduring processing. Bottom wall 215 of RTP apparatus 201 may be coated orprovided with a reflector 211 for reflecting energy onto the backside ofwafer or substrate 101. The RTP apparatus 201 may include a plurality offiber optic probes 271 positioned through bottom wall 215 of RTPapparatus 201 to detect the temperature of wafer or substrate.

The plasma applicator 280 generally includes a body 282 surrounding atube 284 where a plasma of ions, radicals, and electrons is generated.The tube 284 may be made of quartz or sapphire. The tube 284 preferablydoes not have any electrical bias present that might attract chargedparticles, e.g., ions. A gas inlet 286 is disposed at one end of thebody 282 and opposing to a gas outlet 288 that is located at the otherend of the body 282. The gas outlet 288 is in fluid communication withthe RTP apparatus 201 through a delivery pipe 290 such that radicals ofthe plasma generated within the tube 284 are supplied to the processingregion 213 of the RTP apparatus 201. The gas outlet 288 may have adiameter larger than gas inlet 286 to allow the excited radicals to beefficiently discharged at desired flow rate and to minimize the contactbetween the radicals and the tube 284. If desired, a separate orificemay be inserted into tube 284 at the gas outlet 288 to reduce the tube'sinner diameter. The diameter of the gas outlet 288 (or orifice, if used)can be selected to optimize the pressure differential between theprocessing region 213 and the plasma applicator 280 for nitridationefficiency.

A gas source 292 of nitrogen-containing gas, including, but not limitedto, N₂ gas, may couple to a gas inlet 286 via a first input of athree-way valve 294 and a valve 297 used to control the flow rate of gasreleased from the gas source 292. A second input of the three-way valve294 may be coupled to another process gas source 298 including, but notlimited to, oxygen-containing gas, silicon-containing gas, or inner gas.A flow controller 296 is connected to the three-way valve 294 to switchthe valve between its different positions, depending upon which processis to be carried out. The flow controller 296 also functions in asimilar fashion to control the three-way valve 294 and the valve 317 toprovide an appropriate process gas flow from gas source 298 to theprocess chamber.

The plasma applicator 280 may be coupled to an energy source (not shown)to provide an excitation energy, such as an energy having a microwavefrequency, to the plasma applicator 280 to excite the process gastraveling from the gas source 292 into a plasma. In the case wherenitrogen-containing gas, for example, N₂, is used, the microwaveexcitation in plasma applicator 280 produces N* radicals, positivelycharged ions such as N⁺ and N₂ ⁺, and electrons in the tube 284. Bylocating the plasma applicator 280 remotely from the processing region213 of RTP apparatus 201, a plasma source can be selectively generatedto limit the composition of the plasma exposed to substrate 101 topredominantly radicals. It has been observed that ions collisions can befurther promoted by using an improved delivery pipe 290 such that all orthe majority of ions generated by the excitation of the process gas toform a plasma outlive their ionic lifetime and become charge neutralbefore reaching the processing region 213. In other words, thecomposition of the plasma that is supplied to the inlet port 275 of theRTP apparatus 201 is predominantly radicals.

FIG. 3 illustrates a schematic and fragmentary cross-sectional side viewof an exemplary delivery pipe 300 that may be used in place of thedelivery pipe 290 of FIG. 2 according to one embodiment of the presentdisclosure. For the purpose of simplicity and clarity of illustration,elements in the drawings have not been drawn to scale. The delivery pipe300 generally includes a mounting sleeve 302 and an inlet member 304connecting to the mounting sleeve 302. The mounting sleeve 302 and theinlet member 304 each include a hollow cylindrical body defining alongitudinally extending space, for example, sleeve passageway 306 andinlet passageway 308. The profile of the passageway 306, 308 may be anyshape such as circular, oval, square, rectangular, or irregular. One endof the mounting sleeve 302 may be bolted to the gas outlet 288 of thebody 282 of the plasma applicator 280 (partially shown) so that thesleeve passageway 306 in the mounting sleeve 302 is aligned with andcoupled to the tube 284 at the gas outlet 288. Another end of themounting sleeve 302 is connected to the inlet member 304 so that theinlet passageway 308 in the inlet member 304 is substantially alignedwith the sleeve passageway 306 in the mounting sleeve 302. In certainexamples, the diameter of the mounting sleeve 302 may be graduallyreduced along the longitudinal axis of the mounting sleeve 302 to matchthe diameter of the inlet member 304. The mounting sleeve 302 and theinlet member 304 may be made of a material that does not causerecombination of the N* radicals. For example, the mounting sleeve 302and the inlet member 304 may be made of silicon, silicon nitride, boronnitride, carbon nitride, sapphire or alumina (Al₂O₃). While the deliverypipe 300 is shown and described as two separate components (i.e., themounting sleeve 302 and the inlet member 304) being connected to oneanother, the disclosure contemplates a delivery pipe formed from asingle-piece integrated body with a passageway connecting to the inletport 275 of the RTP apparatus 201.

As can be better seen in FIG. 4, which illustrates a schematic andfragmentary top view of the delivery pipe 300 and the RTP apparatus 201,the inlet member 304 may be configured as an adapter which is coupled tothe inlet port 275 in the side wall 214 of the RTP apparatus 201. Itshould be noted that some elements in FIG. 4 have been omitted and notdrawn to scale for the purpose of simplicity and clarity ofillustration. The inlet member 304 may include a flange 310 extendingwholly around the outer surface of the inlet member 304. A portion ofthe inlet member 304 may be extended into the side wall 214 such that anoutermost face 312 of the flange 310 is bolted to the interior surface214 b of the side wall 214. Alternatively, the outermost face 312 of theflange 310 may be bolted to the exterior surface 214 a of the side wall214 and configured in a way that the inlet passageway 308 is coupled tothe inlet port 275. In either case, the delivery pipe 300 is coupled tothe inlet port 275 in such a way that a longitudinal axis “A” of theinlet passageway 308 in the inlet member 304 intersect at an angle θwith respect to a longitudinal axis “B” of the inlet port 275. Theflange 310 may extend in a direction at a desired angle “α” relative tothe longitudinal axis “A” of the inlet passageway 308 as long as thatthe outermost face 312 of the flange 310 is substantially flush withinterior surface 214 b of the side wall 214. In one embodiment, theangle “a” may range from about 20 degrees to about 80 degrees, such asabout 45 degrees to about 70 degrees. The angle θ between thelongitudinal axis “A” of the inlet passageway 308 and the longitudinalaxis “B” of the inlet port 275 may range between about 10 degrees andabout 70 degrees, such as about 20 degrees and about 45 degrees. In oneexample, the angle α is about 45 degrees or above, for example about 60degrees. The angle α or θ should not be limited as defined herein andmay vary as necessary. Having the delivery pipe 300 positioned at anangle relative to the inlet port 275 promotes collision of ions orreaction of ions with electrons or other charged particles since theions lose their momentum through collisions when hitting the interiorsurface of the inlet port 275. Therefore, substantially all ions createdby the excitation by the energy source are eliminated prior to enteringthe processing region 213. While the delivery pipe 300 is shown anddescribed to include the flange 310, the flange 310 may be omitted aslong as the delivery pipe 300 is coupled to the RTP apparatus 201 at anangle that would promote collision of ions or reaction of ions withelectrons or other charged particles.

In addition to the bent pipe structure as described herein, the deliverypipe 300 may be constructed of a length such that, for a given flow rateof a process gas (e.g., a given plasma generation rate), substantiallyall ions are extinguished or reacted with electrons or other chargedparticles to lose their excited state prior to existing the deliverypipe 300. The length of tube 284 and delivery pipe 300 necessary toextinguish substantially all the ions of a plasma at a given source gasflow rate may be determined experimentally or by lifetime calculations.In one embodiment, the tube 284 may have a length of about 5 inches toabout 12 inches with an inside diameter of about 0.5 inches to about 2inches. The length of the delivery pipe 300 (including the inlet and thesleeve passageways 306, 308) may vary from about 5 inches to about 25inches, for example about 16 inches or above. The diameter of thepassageway 306, 308 may be adjusted to optimize the pressuredifferential between the plasma applicator 280 and the processing region213. In one embodiment, the diameter of the passageway 306, 308 is in arange between about 0.5 inches and about 2 inches, for example about0.65 inches and about 1.5 inches in diameter. If desired, either one orboth of the passageways 306, 308 may have a diameter graduallydecreasing or increasing in the direction of flow to promote ion loss.In various embodiments, the total length of the tube 284 and thedelivery pipe 300 may be between about 8 inches to about 35 inches, forexample about 20 inches or above. It is believed that a converging flowof plasma will promote ions collisions. The compression ratio, definedas cross sectional area of plasma generation area, (e.g., the tube 284)to cross sectional area of smallest diameter before the inlet port 275(e.g., the inlet passageway 308) may be about 2 or above, for examplebetween about 5 and about 10 or above.

By separating the plasma generation area (i.e., plasma applicator 280)and the processing region 213 physically with an improved delivery pipe300 being positioned at an angle relative to an inlet port 275 of theRTP apparatus that promotes recombination of ionic species, greaterselectivity of nitridation of silicon or polysilicon floating gate 106is obtained. In an embodiment where a NAND flash memory device having afloating gate 106 with silicon or polysilicon surface is treated with aselective nitridation process performed by the apparatus describedherein, selectivity of nitridation of silicon or polysilicon floatinggate 106 to STI region 108 may be increased to up to about 100:1 with anitrogen dose of about 5×10¹⁵ atoms/cm² to about 15×10¹⁵ atoms/cm², suchas about 20×10¹⁵ atoms/cm² or up, for example about 25×10¹⁵ atoms/cm²,in the surface of silicon or polysilicon floating gate 106.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

1. A method for processing a substrate in a processing region of aprocess chamber, comprising: generating and flowing plasma species froma remote plasma source to a delivery member having a passageway; flowingplasma species from the passageway to an inlet port formed in a sidewallof the process chamber, wherein the plasma species are flowed at anangle of about 10 degrees to about 70 degrees with respect to alongitudinal axis of the inlet port into the inlet port to promotecollision of ions or reaction of ions with electrons or chargedparticles in the plasma species such that ions are substantiallyeliminated from the plasma species before entering the processing regionof the process chamber; and selectively incorporating atomic radicalsfrom the plasma species in silicon or polysilicon regions of thesubstrate.
 2. The method of claim 1, wherein the delivery member isdisposed between the remote plasma source and the process chamber. 3.The method of claim 1, wherein the plasma species are flowed at an angleof about 20 degrees to about 45 degrees with respect to the longitudinalaxis of the inlet port.
 4. The method of claim 1, wherein the passagewayhas a length between about 5 inches and about 25 inches.
 5. The methodof claim 1, wherein the passageway has a diameter in a range betweenabout 0.5 inches and about 2 inches.
 6. the The method of claim 1,wherein the plasma species are generated at a pressure of about 0.3 Torrto about 20 Torr and provided to the delivery member at a flow ratebetween about 1 sLm and about 20 sLm.
 7. A system, comprising: a remoteplasma chamber comprising a tube, the tube defining a plasma regiontherein; a process chamber defining a substrate processing regiontherein, the process chamber comprising an inlet port disposed in asidewall of the process chamber, the inlet port being in fluidcommunication with the substrate processing region; and a deliverymember in fluid communication with the remote plasma chamber and theprocess chamber, wherein the delivery member comprises an inlet membercoupling to the inlet port, and a longitudinal axis of the inlet memberintersects at an angle between about 10 degrees and about 70 degreeswith respect to a longitudinal axis of the inlet port.
 8. The system ofclaim 7, wherein the delivery member is disposed between the remoteplasma chamber and the process chamber.
 9. The system of claim 7,wherein the angle is in a range between about 20 degrees and about 45degrees.
 10. The system of claim 7, wherein delivery member has a lengthof about 5 inches to about 25 inches.
 11. The system of claim 7, whereindelivery member has a diameter gradually decreasing or increasing in thedirection towards the inlet port.
 12. The system of claim 11, whereinthe diameter of the delivery member is in a range between about 0.5inches and about 2 inches.
 13. The system of claim 7, wherein the tubehas a first cross sectional area and the delivery member has a secondcross sectional area, and a ratio of the first cross sectional area tothe second cross sectional area is about 2 or above.
 14. The system ofclaim 13, wherein the ratio is between about 5 and about
 10. 15. Thesystem of claim 7, wherein the delivery member comprises a materialselected from the group consisting of silicon, silicon nitride, boronnitride, carbon nitride, sapphire and alumina.
 16. A system, comprising:a process chamber defining a substrate processing region therein, theprocess chamber comprising an inlet port disposed in a sidewall of theprocess chamber, the inlet port being in fluid communication with thesubstrate processing region; and a delivery member comprising an inletmember, the delivery member coupling to the inlet port, and alongitudinal axis of the inlet member intersects at an angle betweenabout 10 degrees and about 70 degrees with respect to a longitudinalaxis of the inlet port.
 17. The system of claim 16, wherein the angle isin a range between about 20 degrees and about 45 degrees.
 18. The systemof claim 16, wherein delivery member has a length of about 5 inches toabout 25 inches.
 19. The system of claim 16, wherein delivery member hasa diameter gradually decreasing or increasing in the direction towardsthe inlet port.
 20. The system of claim 19, wherein the diameter of thedelivery member is in a range between about 0.5 inches and about 2inches.